2017-02-21

3D printing materials

When I were a lad... OK, well, maybe just a few years ago when I started playing with 3D printers, there was PLA and ABS to play with.

Now there is a lot more, and interestingly the "quality" of the various plastics you can buy really does matter.

PLA (Polylactic Acid) is one of the most common, and usefully it is biodegradable and generally made from renewable sources, so all good. It tends to melt at around 150C, but will be soft well below that. So not ideal for all applications.

I have to say that one company stands out in this market as far as I can see, and that is ColorFabb. I have tried several makes of PLA so far, and you really can tell the difference with the ColorFabb plastic. It is just better and more precise. I printed a model I made recently recently all in different colours, and that meant using lots of different samples and reels I had from different suppliers. It is an educational toy for my grandson. The blocks stack up in order and are all printed from PLA. The ColorFabb blocks fit perfectly, the others are stiff, and not as good. Something is different between them.

The ColorFabb is perhaps a tad more expensive, but they even do some bulk/cheap spools as well. And the range of colours they do, as you may guess from the name, are impressive. I don't have the whole set, else this stack would have been a lot easier to make!

But it all starts to get interesting when you go beyond simple coloured PLA.

ColorFabb XT

ColorFabb have some interesting materials including their XT which is a higher temperature and higher strength and apparently food grade. I have been playing with settings and managed to get things printing reasonably well with it, but have found a snag with the TAZ 6 and the ColorFabb XT! The plastic seems to ooze out of the nozzle during bed levelling and seems almost impossible to stop this hence the bed levelling keeps failing. This is crazy, I know, but that is what is happening. Obviously the first thing I printed had some of the previous PLA in the nozzle to push out and was fine, but the second thing I printed was a nightmare. Solvable, but a challenge. Apart from being stronger and higher temperature tolerant I am not that convinced the XT is as good as the PLA.

ColorFabb nGen

They have also come up with a new plastic (also Eastman Amphora) which is apparently very good. I have had some challenges getting the settings right for this, and still working on it. But it does seem quite good. It only costs about 50p a reel more than the straight PLA. Again, and impressive range of colours available. One of the issues with printing is the temperature stability - when things cool they change shape. This could be a really good answer to that.

ColorFabb Metals!

Yes, metal! They do PLA with bronze, copper, steel, and brass mixed in. What struck me, and should have been obvious, is how small the reel is as it is sold by weight, and metal is heavy. It prints like normal PLA, but apparently can wear the nozzle somewhat. You can feel how heavy it is even in the printed model. The trick seems to be to use metal polish on the finished model to bring up the metallic surface and shine. You can make a bronze bust that looks like a bronze bust!

ColorFabb wood

They also do wood filled. Well... wood, bamboo, and cork. I have only used the fine wood so far and the result is like something carved out of MDF. It is quite interesting - more than simply a different colour.

ColorFabb Carbon Fibre

And finally - one I have yet to try - carbon fibre filled PLA. I have a reel here - it is apparently somewhat wearing on the nozzle, but is strong, and very black.

Conclusion...

I am currently working on trying out the nGen and PLA ColorFabb stuff, getting the settings right and working out which gives the best results. I suspect the nGen when I have it right - currently a slight issue with "bridging" over a space in the prints. Both are very consistent results, very good results, the best kind of results, bigly, and consistent colours (sorry). I am impressed. I am sorry to say I am not actually so impressed with some of the other PLA suppliers.

Anyway, this gives us a good range of colours and materials for the 3D printing services we sell, and some expertise and experience to back that up.

XT Harder to print, indeed I had issues on bed levelling. Very hard and shiny surface, high temperature, food grade, may be useful, but I struggled to get a nice clean print.

PLA+metal prints just like PLA, but is heavier and so somewhat more expensive than it looks (sold by weight) - needs finishing (some good videos on youtube for that) but interesting results. Surprisingly good at overhang.

PLA+wood prints just like PLA, but result is very much like carved MDF with fine texture and looks like wood. Not tried cork yet.

XT CF20 Actually not that bad to print, hotter as is XT, sticks well to hot bed, very black matt finish, and result is surprisingly flexible as well as strong. I did have issues with printing fine detail. I was surprised how flexible to be honest, but still very string - could make a good mobile phone case I expect.

nGen prints quite nicely once you have settings right (bridging was fun). Very "clean" print. It can be "sticky" while printing and so initial print shirt/brim needed tweaking as can end up dragging a bit of sticky filament at start. End result feels really solid/strong, maybe a bit brittle but hard. Sticks very well to hot bed whilst printing.

I actually think the nGen will be the winner over PLA/PHA or XT to be honest, but need to do a bit more testing. Obviously metal/wood work well where you want that aesthetic effect. The carbon fibre would fit some specific applications I expect, when you need something strong and flexible.

Next step is probably to try a print of a couple of classic things that are tricky, and see how each copes. Then I can blog in more details. My key tests for are a DALEK and a Twisting Valentine's Heart. It will be a while before I find time to try each material with these, so watch this space.

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